CEFAZOLIN AND DEXTROSE
Clinical safety rating: safe
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
Bactericidal agent inhibiting bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), disrupting peptidoglycan cross-linking, leading to cell lysis. Dextrose provides osmotic diuresis and energy source.
| Metabolism | Cefazolin undergoes minimal hepatic metabolism; majority excreted unchanged in urine via glomerular filtration and tubular secretion. Dextrose undergoes cellular metabolism to carbon dioxide and water. |
| Excretion | Renal (80-90% unchanged via glomerular filtration and tubular secretion); biliary/fecal (<5%) |
| Half-life | 1.8 hours (prolonged to 20-40 hours in severe renal impairment, CrCl <10 mL/min) |
| Protein binding | 80-86% bound to albumin |
| Volume of Distribution | 0.12-0.14 L/kg (primarily extracellular fluid) |
| Bioavailability | IM: ~100% (rapid and complete absorption) |
| Onset of Action | IV: Immediate; IM: 15-30 minutes |
| Duration of Action | 6-8 hours after IV/IM administration; prolonged in renal impairment |
| Molecular Weight | 454.5 |
1-2 g IV/IM every 8 hours; maximum 12 g/day.
| Dosage form | INJECTABLE |
| Renal impairment | CrCl 30-60 mL/min: 0.5-1 g every 12 hours. CrCl <30 mL/min: 0.5-1 g every 24 hours. |
| Liver impairment | No adjustment required; primarily renally eliminated. Use standard dosing. |
| Pediatric use | 25-50 mg/kg/day IV/IM divided every 8 hours; maximum 100 mg/kg/day. |
| Geriatric use | Dose based on renal function; consider CrCl and adjust per renal guidelines. Typical starting dose: 1 g IV/IM every 12 hours. |
| 1st trimester | Cefazolin crosses the placenta and is generally considered safe in the first trimester when clearly indicated; no known teratogenic effects in animal studies. |
| 2nd trimester | Safe for use in the second trimester; no evidence of fetal harm. |
| 3rd trimester | Safe for use in the third trimester; commonly used for prophylaxis during cesarean section. |
Clinical note
Probenecid may decrease cephalosporin excretion Nephrotoxicity may occur with concurrent use of potent diuretics.
| FDA category | Human |
| Placental transfer | Cefazolin crosses the placenta readily; therapeutic levels achieved in fetal serum and amniotic fluid. |
| Breastfeeding |
■ FDA Black Box Warning
None
| Common Effects | Diarrhea |
| Serious Effects |
Hypersensitivity to cefazolin or any cephalosporin antibioticHistory of severe immediate hypersensitivity reaction to penicillins or other beta-lactams
| Precautions | Hypersensitivity reactions including anaphylaxis, Clostridium difficile-associated diarrhea (CDAD), Renal impairment requiring dose adjustment, Superinfection with prolonged use, Coagulation abnormalities (rare), Seizures with high doses in renal impairment |
| Food/Dietary | No specific food interactions. However, patients on parenteral nutrition should be monitored for electrolyte imbalances. Dextrose content may affect blood glucose; adjust diabetic diet accordingly. |
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| Cefazolin is excreted into breast milk in low concentrations. It is generally considered compatible with breastfeeding, but may alter infant gut flora. Monitor for diarrhea or allergic reaction. |
| Lactation Rating | L1 (Safest) |
| Teratogenic Risk | Cefazolin is a first-generation cephalosporin classified as FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, and there are no adequate, well-controlled studies in pregnant women. However, cephalosporins are generally considered safe during pregnancy. First trimester: Limited data, but no known teratogenic effects. Second and third trimesters: Considered safe; no documented fetal harm. Cefazolin crosses the placenta achieving therapeutic concentrations in fetal serum and amniotic fluid. Overall, risk is low. |
| Fetal Monitoring | No specific monitoring required. Standard obstetric care applicable. For repeated use or high doses, monitor maternal renal function and complete blood count due to potential neutropenia or thrombocytopenia. Fetal monitoring as per routine pregnancy management. |
| Fertility Effects | No adverse effects on fertility reported in animal studies or human data. Cefazolin does not affect spermatogenesis or ovarian function. No evidence of impairment of fertility from cephalosporins. |
| Clinical Pearls | Cefazolin is a first-generation cephalosporin with activity against gram-positive cocci (except MRSA) and some gram-negative rods. It is often used for surgical prophylaxis. Dextrose solutions may cause hyperglycemia in diabetic patients; monitor blood glucose. Cefazolin has a short half-life (~1.8 hours) and requires dosing adjustment in renal impairment (CrCl <55 mL/min). It is compatible with most IV fluids but avoid mixing with calcium-containing solutions in neonates due to precipitation risk. Pain at injection site is common; deep IM administration preferred. |
| Patient Advice | Take this medication exactly as prescribed; complete the full course even if you feel better. · Report any signs of allergic reaction: rash, hives, itching, difficulty breathing, or swelling of face/throat. · If you have diabetes, monitor blood glucose closely as the dextrose solution may increase blood sugar. · This medication may cause diarrhea; if severe or bloody, contact your doctor immediately. · Inform your healthcare provider if you have kidney disease, colitis, or allergies to penicillins or cephalosporins. |